As well known to those skilled in the art, drive belt assemblies incorporate two or more pulleys. one driving, two or more driven, wherein the system includes a drive belt to transmit power from the driving to the driven pulleys. It is often desirable to have a drive belt configuration wherein the drive belt may be disengaged from the power transmission mode by releasing belt tension applied to the belt by a movable idler pulley. One of the major problems presented in such an arrangement arises when the idler pulley releases belt tension. At such time, it is necessary to retain the belt in very close proximity to the driving pulley, which is still rotating usually at a high speed, and the driven pulleys so that the belt can be accurately reengaged for power transmission at any time by the operator through movement of the idler system. Retention of the belt in such close proximity is typically accomplished by placement of belt guides which allow the belt to relax off of the driving pulley, stopping power transmission even though the driving pulley continues to rotate at a high speed, but restrains the belt so as to keep the belt from falling too far away from the pulley system. The belt guides also keep the belt restrained in a proper shape so that the belt is held just far enough away from the driving pulley and cannot engage the rotating surface of the driving pulley at a time when no power transmission is desired.
Drive belt guides are also utilized in drive belt configurations where no idler system is used. In such configurations, the drive belt guide's sole function is to restrain and guide the belt during the power transmission mode, i.e., when the belt is engaged and is being driven.
In all cases, accurate placement and fastening of the drive belt guides is important so that the drive belt will be properly restrained as outlined above.
But, proper locating fastening and orientation retention of drive belt guides has been a longstanding problem. Historically the guides were constructed of round steel bar stock and were formed at one end so as to create an eye hook opening for accepting a fastener such as a bolt for clamping the belt guide to an adjacent mounting surface. The belt guide, as formed had no sharp protrusions on its clamping surface. Typically the installer of the driver belt guide had a great deal of difficulty in maintaining the proper belt drive guide orientation while tightening down the clamping bolt. As the bolt was tightened to its final turn it tended to grab the belt guide and rotate it away from the desired orientation of the guide. This forced the installer to force the guide back to its correct orientation after tightening by pounding the guide against the clamping force of the bolt. The installer was also often forced to attempt to hold the guide, during tightening, in its proper location, which was rather difficult. The installer would also often try to compensate for the anticipated unwanted rotational displacement by setting the initial orientation of the belt guide a number of degrees counter clockwise before tightening, hoping that the final location, after tightening the bolt, would be proper.
Even after the belt guide had been properly located and tightened, the belt guide of the prior design was still prone to harmful movement due to shock and vibrational loads in the machine. Furthermore, the drive belt itself would, from time to time contact the belt guide causing varying degrees of movement.
U.S. Pat. No. 1,280,682, issued to F. B. Dickinson, discloses a belt guide which incorporates a washer-clamp that has a set of protrusions which are used to prevent rotational displacement of a belt guide. However, the protrusions or tabs in the Dickinson belt guide washer-clamp do not prevent rotational displacement by frictionally engaging an adjacent mounting surface. These protrusions are used to actually contact the arms of the guide itself and thus prevent rotational displacement in that fashion. The Dickinson belt guide washer-clamp further attempts to prevent rotational displacement by utilizing a single tab on the washer that can be bent up against the flats of the bolt head of the bolt used to attach the guide and washer to the apparatus. While the Dickinson belt drive washer-clamp provides a means for preventing rotational displacement of the belt guide, it must be noted that the Dickinson clamp requires an additional forming step upon installation.
Another prior design utilized a single piece belt guide formed of a length of cold drawn steel round bar stock. The length of bar stock was formed so as to have an eyelet at one end for accepting a fastener and a finger like projection at the other end extending adjacent to a drive belt. The eyelet of the guide was formed so as to provide a suitable mounting surface so that the guide would mount flush on an adjacent mounting surface to which the guide was clamped when a bolt and nut combination was inserted and tightened down through the eyelet and mounting surface openings. This belt guide clamping technique did not eliminate the problem of the belt guide's tendency to move during the tightening of the fastener. The eyelet of the belt guide tended to be rotationally displaced by the torque applied to the fastener during tightening since the eyelet surface contacting the other adjacent mounting surface had a relatively low frictional resistance to the applied torque. The resulting rotational displacement caused the portion of the guide extending adjacent to the drive belt to be moved away from the desired position adjacent to the belt. The installer then was required to reset the position of the belt guide so that it would extend adjacent to the belt.
In addition to the prior art described above, there have been other belt guide techniques utilized. While each of these techniques were useful for their intended purposes, they each presented problems in that they typically did not prevent unwanted rotational displacement during the tightening process.
The present invention addresses the problems associated with prior art belt guide clamping techniques. In particular, a preferred drive belt guide according to the present invention accommodates ease of positioning and tightening the drive belt guide in a drive belt system in that it incorporates a member including means for accepting a fastener where the fastener accepting means establishes the pivot point for the member a sharp protrusion spaced away from the pivot point, and an elongate finger projecting away from the pivot point and from the protrusion and projecting adjacent to a drive belt. The drive belt system also incorporates fastening means for clamping the member to the mounting surface so as to frictionally engage the protrusion to the mounting surface, whereby the member will remain rotationally fixed relative to the pivot point and the finger of the member will remain adjacent to the drive belt once the member is fastened to the mounting surface.